Trump told him he didn't care if it took until Friday, Politico reported, quoting three senior White House officials, but no longer.

The bill is moving at relative lightning speed considering its massive size and scope, Politico noted. Still, too many delays could signal a loss of momentum for one of Trump's and the party's most-touted issues.

"If we get to Friday afternoon and we still haven't seen a bill, people will start to get genuinely concerned," one source close to the administration told Politico.

"Every day that it gets delayed is a setback if we're aiming to sign a bill by Christmas Eve," said Stephen Moore of the Heritage Foundation, who also is an informal adviser to Trump on the economy.

Thursday still appears to be a "go" for House Republicans to announce their tax reform bill.That's fine with President Donald Trump, who backs the bill, but the administration doesn't want to see delays stretch into next week, Politico reports.